You want to know what people think. If what you wrote is true, this is what I think:
You say this:
Now I don't feel like I had any wrong done to me.
I enjoyed the experience as its every teenage boys dream to do
This is all well and good. You were a boy either in or just out of puberty. Your sex drive and curiosity about sex were high. You enjoyed it physically because your body is designed by nature to enjoy sex. Your dick felt good. But sometimes a dream should stay a dream until you are ready to handle the reality. Otherwise the person can be left feeling mixed up about sex, relationships etc, if not worse. Now you say:
However I spent years feeling guilty for my mum and I felt I had betrayed her. I also
Could not talk to anyone about my actions in fear of upsetting my mother.
You felt weird about what had happened. This is normal too. You were 14; she was 40. Sounds like at some level you feel it was wrong (what the woman did, not what you did), or are wondering if it was. That's one reason why people post on here about this kind of thing. For a clue about how you feel now, let's consider this...
if I saw a 40 year old lady trying it on with this boy I'd think it was disgraceful.
You were sexually abused. It doesn't really matter whether the young victim is male or female, if they are (a) below the age of consent (b) unready emotionally to handle a sexual relationship with someone much older (c) were coerced into it by someone older and seemingly more powerful, then it's abuse. You check (a) (b) and (c). I have heard disgusting men say (of having sex with young girls), "If there's grass on the pitch..." meaning that if the girl appears physically sexually mature then it's OK. The law takes a different view, just as it does if the sexes are reversed. If a woman says, "Well, he had a boner..." that's just the same situation. That woman committed a sex crime, and in the UK could be prosecuted, jailed, and made to sign the sex offender's register. I am not saying you have got to do this, but if you feel that you have been sexually abused, you can get help. In the UK whatever your age you can call Childline in confidence and talk things over. They will not ask for details or make you go to the police. In most Western countries there are help lines you can call to get referred for counselling help. I wonder how many more boys this woman interfered with, and continues to interfere with.